a
2
+
10
a
+
25
Rewrite
25
25
as
5
2
5
2
.
a
2
+
10
a
+
5
2
a
2
+
10
a
+
5
2
Check the middle term by multiplying
2
a
b
2
a
b
and compare this result with the middle term in the original expression.
2
a
b
=
2
⋅
a
⋅
5
Answer: C
Step-by-step explanation:
The sequence is arithmetic as it goes down 3 every time
Arithmetic nth term formula is an=a1+d(n-1)
an=7-3(n-1)
an=7-3n+3
an=-3n+10
To find the 100th term substitute n for 100
a100=-3(100)+10
a100=-300+10
a100=-290
The 100th term is -290
I believe its 84, because basically if you take the 6×6 for the top layer it equals 36 and there's two layers so 36+36= 72, then you add the top half which is 12, which would equal 84.
